Methods for optimal multi-channel assignments in vehicular ad-hoc networks

Abstract

A communications path is established among an ordered sequence of moving nodes, representing vehicles. Available channels may differ from one node to the next node and a node cannot use the same channel for both receiving and transmitting information. Three methods are described that provide an optimal sequence of channel assignments between the nodes. A sequence of channel assignments is called optimal if it establishes a communications path from the first node in the sequence to the last node in the sequence, or, if such a path does not exist, from the first node to the farthest node possible in the sequence. The first method uses a depth-first search starting from the first node in the sequence. The second method uses a “look ahead” scheme in the depth-first search method. The third method requires only a single pass through the sequence of nodes by identifying optimal channel assignments in subsequences of nodes without a need for backtracking.

Description

FIELD OF INVENTION[0001]The present invention relates to channel assignments in mobile ad-hoc networks and more specifically, the invention concerns assignment of channels in ad-hoc vehicular networks comprising an ordered sequence of moving vehicles.BACKGROUND OF THE INVENTION[0002]A mobile ad-hoc network (MANET) is formed by multiple moving nodes equipped with wireless transceivers. The mobile nodes communicate with each other through multi-hop wireless links, wherein every node can transmit and receive information. Mobile ad-hoc networks have become increasingly important in areas where deployment of communications infrastructure is difficult. Such networks are used for communications in battle fields, natural disasters, fleets on the ocean, and so forth Numerous papers have been published on this topic. For example, C. Xu, K. Liu, Y. Yuan, and G. Liu, “A Novel Multi-Channel Based Framework for Wireless EEE 802.11 Ad Hoc Networks”, Asian Journal of Information Technology, 5, 44-4...

AI Technical Summary

Benefits of technology

[0007]The present invention focuses on establishing a communications path among an ordered sequence of moving nodes, representing vehicles. The sequence of nodes can be viewed as a directed linear tree topology where a link interconnects a node only to its successor node in the ordered sequence. A channel is used to send information from one node to the next node on a wireless link. The set of available channels may differ from one node to the next node. Each of the available channels at a node can be used for receiving information from its predecessor node in the sequence or for transmitting information to its successor node in the sequence. However, the same channel cannot be used at a node for both receiving and transmitting information. Using information regarding the set of available channels at each of the nodes in the ordered sequence of nodes, the invention provides methods that determine an optimal sequence of channels assigned to the wireless links connecting the nodes. A sequence of channel assignments is called optimal if it establishes a communications path from the first node in the ordered sequence to the last one, or, if such a path does not exist, it establishes a communications path from the first node in the ordered sequence to the farthest node possible. The present invention describes three methods that find an optimal sequence of channel assignments. The first method uses a depth-first search starting from the first node in the sequence. The second method improves upon the channel selection rule in a node by using a “look ahead” scheme that may reduce the computational effort of the depth-first search method. The third method requires only a single pass through the sequence of nodes by identifying optimal channel assignments in subsequences of nodes without a need for backtracking, resulting in computational effort that is proportional to the number of nodes in the ordered sequence of nodes.

Problems solved by technology

However, the same channel cannot be used at a node for both receiving and transmitting information.

The third method requires only a single pass through the sequence of nodes by identifying optimal channel assignments in subsequences of nodes without a need for backtracking, resulting in computational effort that is proportional to the number of nodes in the ordered sequence of nodes.

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